[Bug 258949] IPv4 alias on Chelsio T6225-CR, ping: sendto: No route to host

From: <bugzilla-noreply_at_freebsd.org>
Date: Tue, 05 Oct 2021 16:15:06 UTC

            Bug ID: 258949
           Summary: IPv4 alias on Chelsio T6225-CR, ping: sendto: No route
                    to host
           Product: Base System
           Version: 13.0-RELEASE
          Hardware: amd64
                OS: Any
            Status: New
          Severity: Affects Only Me
          Priority: ---
         Component: kern
          Assignee: bugs@FreeBSD.org
          Reporter: jasonmader@gmail.com

FreeBSD 13.0-RELEASE-p4

I haven't been able to recreate this on anything other than a system with the
Chelsio T6225-CR, but an IPv4 alias only (IPv6 aliases work fine) with a /32
netmask such as,, doesn't work,

cc0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 9000      
        inet netmask 0xffffffe0 broadcast
        inet netmask 0xffffffff broadcast

PING ( 56 data bytes
ping: sendto: No route to host

But change the netmask to /31 and the ping will work.

ifconfig_cc0="inet mtu 9000"

Destination        Gateway            Flags     Netif Expire link#1             U           cc0    link#1             UHS         lo0    link#1             UH          cc0

On FreeBSD 11.2 with an Intel interface it would have looked like, link#1             U           ix0    link#1             UHS         lo0    link#1             UHS         lo0 link#1             U           ix0

t6nex0: <Chelsio T6225-CR> mem
0xdb200000-0xdb27ffff,0xda000000-0xdaffffff,0xdb684000-0xdb685fff irq 120 at
device 0.4 on pci12
cc0: <port 0> on t6nex0
cc1: <port 1> on t6nex0
t6nex0: PCIe gen3 x8, 2 ports, 22 MSI-X interrupts, 70 eq, 21 iq

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